Block copolymers have the characteristics of each of their constituent polymer blocks, act accordingly, and are useful in adhesion bonds, polymer surfactants, thermoplastic elastomers, and the like. For example, a block copolymer comprising a methacrylic acid ester polymer block and an acrylic acid ester polymer block is known (Patent Document 1). This block copolymer is excellent in forming processability, transparency, weather resistance and the like and is therefore used in electronic members, industrial members, components of daily necessities, and the like.
Acrylic adhesives are superior to rubber-based adhesives in weather resistance and heat resistance, and are therefore used in adhesive tapes, adhesive sheets, for example. As base polymers for the acrylic adhesive, acrylic random copolymers and acrylic block copolymers are known.
As the acrylic block copolymers, Patent Document 3 discloses a block copolymer comprising a polymer block comprising a methacrylic acid alkyl ester and a polymer block comprising an acrylic acid alkyl ester, as a base polymer for a pressure sensitive adhesive. Patent Document 4 discloses a block copolymer comprising a polymer block mainly composed of a methacrylic acid alkyl ester and having a glass transition temperature of not less than +110° C. and a syndiotacticity of not less than 70% and a polymer block mainly composed of an acrylic acid alkyl ester and/or a methacrylic acid alkyl ester and having a glass transition temperature of not more than +30° C., as a base polymer for a hot-melt adhesive.